Take-All disease is a serious problem in the production of cereals, particularly wheat and barley. It is caused by the soil-borne fungus Gaeumannomyces graminis (Gg). The fungus infects the roots of the plant, and grows throughout the root tissue, causing a black rot. The growth of the fungus in the roots and lower stems prevents the plant from obtaining sufficient water and/or nutrients from the soil, and is manifested as poor plant vigor and, in severe instances of disease, by the formation of "whiteheads," which are barren or contain few, shriveled grains. Yield loss results. Gaeumannomyces species also infect other cereal crops, for example, rice and oats; and turf.
Currently the primary means of avoiding crop loss due to infestation of the soil by Gg has been to rotate the crop grown to one which is resistant Gg. However, in areas where the primary crops are cereals, rotation is not a desirable practice, and an effective control agent is greatly desired.
U.S. Pat. No. 5,486,621, hereby incorporated by reference, discloses a unique fungicidal composition, 4,5-dimethyl-N-2-propenyl-2-(trimethylsilyl)-3-thiophenecarboxarnide, which provides superior and unexpected control of Take-All disease. It is an object of this invention to provide novel methods for synthesizing this unique fungicide. In addition, International Application No. PCT/US92/08633 discloses a broad scope of compounds effective against Take-All disease. Objects of the present invention also include providing additional novel compounds which will control the growth of Gg in the soil to reduce crop loss and providing novel methods for preparing such compounds. Further objects of this invention include providing an effective method for control of Take-All disease in plants and fungicidal compositions that may be used for control of Take-All disease as a seed treatment or as a soil treatment.
These and other objects of the invention will be apparent to those skilled in this art from the following description of the invention.